The invention is directed to the broad field of apparatus for purging closed fluid piping or other flow systems of air or other corrosive gases. In particular, water source heat pumps of the type where a liquid, for example, water or brine is used to exchange heat to and from a heat pump. Such a heat pump is known in the art and is typical of that utilized for heating and cooling living or working space. A water source heat pump (WSHP) evaporates refrigerant liquid which absorbs heat from water circulating through pipes and a heat exchanger. An electric motor driven compressor pressurizes refrigerant vapor, raising its temperature and delivers it to the condenser coil in the space where heat from condensation is released and transferred to circulating air. A reversing valve changes the flow of refrigerant through the water heat exchanger to change from heating to a cooling cycle.
This invention is directed to a WSHP system wherein the circulating water pipes comprise a sealed closed loop of high strength plastic pipe which is buried in the ground or in communication therewith either through vertical bores and/or horizontal trenches adjacent and/or surrounding the house or other location being affected. Typically, such a closed loop of piping will consist of as much as four hundred to five hundred feet per ton (of heat pump rating) of piping depending upon the size of the system, the size and type of pipe and the ambient climate conditions.
The problem with such an earth coupled system is in the start-up procedures wherein the piping is to be first filled or thereafter to be refilled. In order to prevent possible freezing most systems use brine as the heat exchange liquid. Thus, because part of the heat exchange system within the heat pump is subject to corrosion, it is necessary to purge the air from the piping system to substantially minimize such corrosion.